Constraints on the intergalactic magnetic field from F e r m i -LAT observations of GRB 221009A
Year: 2026
Type: article
Abstract: A cosmological origin of magnetic fields in large scale structures of the Universe would require a non-negligible magnetic field in cosmic voids, which, however, remains undetected. Gamma-ray emission from gamma-ray bursts (GRBs) offers the opportunity to indirectly probe such an intergalactic magnetic field (IGMF), as γ rays interact with cosmic radiation fields, producing electron-positron pairs, and initiate an electromagnetic cascade. The deflection of the pairs in the IGMF results in a time-delayed signal at GeV energies. Using observations with the Large Area Telescope of the GRB 221009A, we are able to derive the most stringent constraints to date from the nonobservation of the cascade and rule out magnetic fields B < 2.5 × 10 − 17 G at 95% confidence level for a coherence length larger than 1 Mpc. Our results are comparable to limits obtained from blazar observations but do not suffer from assumptions on the duty cycle of the γ -ray source or whether inverse-Compton scattering losses dominate over the development of plasma instabilities.
DOI: 10.1103/g8rr-g7p4
Institutions: Universität Hamburg, Heidelberg University, Osservatorio di Astrofisica e Scienza dello Spazio, National Institute for Astrophysics, University of Trieste, Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, University of Southern Denmark, Centre for Cosmology and Particle Physics Phenomenology, Astronomical Observatory of Rome, University of Alabama in Huntsville
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Funders: U.S. Department of Energy, National Aeronautics and Space Administration, European Commission, Deutsche Forschungsgemeinschaft, Ministry of Education, Culture, Sports, Science and Technology, Swedish National Space Agency, Centre National d’Etudes Spatiales, Agenzia Spaziale Italiana, Knut och Alice Wallenbergs Stiftelse, Vetenskapsrådet, Centre National de la Recherche Scientifique, Istituto Nazionale di Astrofisica, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, High Energy Accelerator Research Organization, Horizon 2020 Framework Programme, European Research Council, Instituto Nazionale di Fisica Nucleare, Japan Aerospace Exploration Agency, Institut National de Physique Nucléaire et de Physique des Particules, Irish Rugby Football Union, NextGenerationEU
OpenAlex ID: W7124314676